/*
Attempts to load a Graph at the given dir, or creates a new one if no graph repo is found.
If a new graph is fabricated, it will be initialized by:
- creating a new git repo,
- making a blank root commit,
- and tagging it with a branch name that declares it to be a graph repo.
Note if your cwd is already in a git repo, the new graph will not be commited, nor will it be made a submodule.
You're free to make it a submodule yourself, but git quite wants you to have a remote url before it accepts your submodule.
*/
func NewGraph(dir string) *Graph {
g := newGraph(dir)
if g.isHrootGraphRepo() {
// if we can just be a load, do it
return g
} else if g.isRepoRoot() {
// if this is a repo root, but didn't look like a real graph...
util.ExitGently("Attempted to make a hroot graph at ", g.dir, ", but there is already a git repo there and it does not appear to belong to hroot.")
} // else carry on, make it!
// we'll make exactly one new dir if the path doesn't exist yet. more is probably argument error and we abort.
// this is actually implemented via MkdirAll here (because Mkdir errors on existing, and I can't be arsed) and letting the SaneDir check earlier blow up if we're way out.
err := os.MkdirAll(g.dir, 0755)
if err != nil {
panic(err)
}
// git init
g.cmd("init")("--bare")()
g.withTempTree(func(cmd Command) {
// set up basic repo to identify as graph repo
cmd("commit", "--allow-empty", "-mhroot")()
cmd("checkout", "-b", hroot_ref_prefix+"init")()
// discard master branch. a hroot graph has no real use for it.
cmd("branch", "-D", "master")()
})
// should be good to go
return g
}
func (g *Graph) Load(lineage string, gr GraphLoadRequest) (hash string) {
lineage, _ = SplitImageName(lineage) //Handle tags
//Check if the image is in the graph so we can generate a relatively friendly error message
if !g.HasBranch(hroot_image_ref_prefix + lineage) { //HALP
util.ExitGently("Image branch name", lineage, "not found in graph.")
}
g.withTempTree(func(cmd Command) {
// checkout lineage.
// "-f" because otherwise if git thinks we already had this branch checked out, this working tree is just chock full of deletes.
g.cmd("checkout", "-f", git_branch_ref_prefix+hroot_image_ref_prefix+lineage)()
// the gr consumes this filesystem and shoves it at whoever it deals with; we're actually hands free after handing over a dir.
gr.receive(".")
hash = "" //FIXME
})
return
}